2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/219655We construct crude estimates for non-optimality of quantum measurements in terms of their violation of Holevo's simplified minimum-error optimality conditions. As an application, we show that a modification of Barnett and Croke's proof of the optimality conditions yields a convergent iterative scheme for computing optimal measurements.The optimality condition in the prevoius version had already been shown by Holevo. The bounds on non-optimality and convergence of the iterative algorithm are unchangedQuantum Physicstext